The WA42Y-C bellows spring fully open safety valve is suitable as a safety protection device for container equipment or pipeline systems with varying back pressure and toxic and flammable substances. The WA42Y-C bellows spring full opening safety valve is suitable for air, petroleum gas, non corrosive gases, etc. with a working temperature of ≤ 300 ℃. The WA42Y-P bellows spring full opening safety valve produced by Shanghai First Ring Road is suitable for nitric acid and other media with a working temperature of ≤ 200 ℃, and has stable quality.